JPH08302262A - Emulsion ink for pore plate printing - Google Patents

Abstract

PURPOSE: To obtain an emulsion ink for pore plate printing, capable of providing a printed image having a high concentration and fixed qualities, excellent in drying properties, free from ink bleeding, strike-through and offset irrespective of the kind of printing paper and the existence of unevenness on the surface of printing paper. CONSTITUTION: In a water-in-oil type emulsion ink containing an oil phase and a water phase, this emulsion ink for pore plate printing contains as extender pigment in the oil phase, where the amount of the extender pigment contained is 1-50wt.% based on that of the whole emulsion ink. A colorant, a resin, a nonvolatile solvent, a volatile solvent and an emulsifying agent are contained in the oil phase or the resin, the nonvolatile solvent, the volatile solvent and the emulsifying agent are contained in the liquid phase and the colorant, an oil-in-water type resin emulsion and/or a water-soluble polymer compound are contained in the water phase.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an emulsion ink for stencil printing, and more specifically, it provides a printed image of high density and constant quality regardless of the type of printing paper and the presence or absence of irregularities on the surface of the printing paper. The present invention relates to an emulsion ink for stencil printing, which is excellent in ink drying property and has no ink bleeding, strike-through and set-off.

[0002]

2. Description of the Related Art In stencil printing, a stencil printing base paper is used to make a plate, and ink is supplied from perforations formed in the base paper to print on a printing medium such as paper. It is used in a wide range of fields due to its ease of use. As the ink used for stencil printing, water-in-oil (W / O) type emulsion ink is generally used. The emulsion ink is dried by allowing the ink component to permeate the inside of the printing paper, which is the material to be printed, and by scattering the water component into the atmosphere (JP-A-61-255967).
Japanese Patent Laid-Open No. 64-14284, Japanese Laid-Open Patent Publication No. 4-1
32777, JP-A-5-117565, etc.).

However, in the conventional W / O type emulsion ink, the ink component penetrates into the printing paper when the ink is dried, and at the same time, the coloring agent also penetrates into the printing paper, so that the amount of the coloring agent remaining on the surface of the paper. And the print density is reduced. In addition, since the colorant in the ink penetrates into the printing paper, the so-called ink strike-through phenomenon is likely to occur, in which a reverse printed image can be seen from the back surface of the printing paper.

Further, since the permeation speed of the ink component into the paper differs depending on the type of paper, the density of the printed image obtained by the type of paper used for printing, ink bleeding,
The drawback is that the degree of strike-through and set-off varies. That is, when the permeation speed of the paper is fast, the ink components permeate the inside of the paper with almost no remaining on the paper surface, which lowers the print density and increases the amount of ink strikethrough, while Ink set-off is reduced because it does not remain in the ink. On the other hand, when the permeation rate is slow, the ink components tend to remain on the paper surface, resulting in a higher print density of the printed image and less strike-through. There are many transfers. Therefore, there is a demand for an emulsion ink for stencil printing that can obtain a high-density printed image without being affected by the permeation rate of the ink into the printing paper and at the same time has no strike-through or set-off of the ink.

Further, since the emulsion ink is dried by the permeation of the ink component into the inside of the paper, when stencil printing is carried out using a printing paper having an uneven surface,
Depending on the type of paper, it may be difficult to obtain a glossy print image. This phenomenon is also seen in high-quality paper and medium-quality paper,
Especially, it is remarkable in lower grade paper. Therefore, the quality of the print image to be obtained differs depending on the presence or absence of unevenness on the surface of the paper, and such a phenomenon becomes remarkable when full-color printing is performed. Furthermore, in stencil printing, since the ink is extruded from the perforated portion of the base paper and supplied to the printing paper, the ink must have been imparted with a certain degree of viscosity. When the polymer compound is used, the ink permeation rate decreases, and set-off easily occurs.

[0006]

DISCLOSURE OF THE INVENTION The inventors of the present invention have disclosed in Japanese Patent Application No. 7-24373 that an extender pigment is added to an aqueous phase that can produce a good printed matter without being affected by the permeation rate of ink into a printing paper. A W / O type emulsion ink for stencil printing containing the above was proposed. However, when the emulsion ink penetrates the printing paper, the water phase penetrates after the oil phase penetrates, and the penetration speed of the emulsion ink is most affected by the oil phase component. The penetration speed of the ink and thus the drying property of the ink cannot be improved,
It was found that there was a limit to the effect of preventing ink set-off.
An object of the present invention is to solve the problems of the above-mentioned technology, to obtain a print image of high density and constant quality regardless of the type of printing paper and the presence or absence of unevenness on the printing paper surface, and to dry the ink. An object is to provide an emulsion ink for stencil printing which has excellent properties and does not cause ink bleeding, strike-through and set-off.

[0007]

The inventions claimed in this application are as follows. (1) A water-in-oil (W / O) type emulsion ink having an oil phase and a water phase, wherein an extender pigment is contained in the oil phase. (2) 1 to 1 of the extender pigment based on the total amount of emulsion ink
The emulsion ink for stencil printing according to claim 1, wherein the emulsion ink is contained in an amount of 50% by weight. (3) The emulsion ink for stencil printing according to claim 1 or 2, wherein the oil phase contains a colorant, a resin, a non-volatile solvent, a volatile solvent and an emulsifier. (4) The oil phase contains a resin, a non-volatile solvent, a volatile solvent and an emulsifier, and the water phase contains a colorant and an oil-in-water (O / W) type resin emulsion and / or a water-soluble polymer compound. The emulsion ink for stencil printing according to claim 1 or 2, wherein

In the present invention, since the extender pigment is contained in the oil phase component of the W / O type emulsion ink, the colorant in the oil phase component or the colorant in the water phase component is applied to the surface of the printing paper together with the extender pigment. It can be efficiently retained, the reduction of the print density can be effectively prevented, and the amount of the colorant penetrating into the inside of the printing paper can be reduced to prevent the strike-through of the ink. Furthermore, the liquid component in the oil phase component is immediately separated from the extender pigment, and only the liquid component permeates into the paper, so the permeation speed of the oil phase component becomes faster, and as a result, the permeation speed of the emulsion ink also becomes faster, Dryability is improved and set-off is improved. Further, according to the ink of the present invention, since the irregularities on the paper surface are filled with the ink, the irregularities on the surface are reduced, and it is possible to perform gloss-like printing, and even when printing in full color, it is almost the same regardless of the type of printing paper. Similar images are obtained. Furthermore, since viscosity can be imparted to the stencil printing ink by selecting the type of extender pigment, the ink permeation rate can be improved rather than viscosity imparting with a polymer compound such as a resin component in the oil phase. An ink suitable for stencil printing can be obtained without dropping.

The W / O type emulsion ink in the present invention contains, for example, 10 to 70% by weight of the oil phase (O) component, and
It is produced by gradually adding 0 to 30% by weight of the water phase (W) component and emulsifying. In the present invention, the oil phase component includes an extender pigment. This extender pigment is a non-colored pigment and is different from the coloring agent for coloring. It prevents the coloring agent from penetrating into the inside of the paper when the ink components permeate into the printing paper and retains it on the surface of the printing paper. Have an effect.

The extender pigment is not particularly limited as long as it is water-insoluble fine particles, and for example, clay, talc, clay,
Inorganic particles such as diatomaceous earth, calcium carbonate, barium sulfate, titanium oxide, alumina white, silica, kaolin, mica, aluminum hydroxide, polyacrylic acid ester, polyurethane, polyester, polyethylene, polypropylene, polyvinyl chloride, polyvinylidene chloride,
Organic fine particles such as polystyrene, polysiloxane, phenol resin, epoxy resin and benzoguanamine resin, or fine particles made of a copolymer thereof are used.

The amount of the extender pigment added is preferably 1 to 50% by weight, more preferably 5 to 20% by weight, based on the total amount of the emulsion ink. If the amount of the extender pigment added is too small, the effect on the print density, strikethrough, etc. of the obtained print will be small, and if it is too large, the ink will be unsuitable for stencil printing, that is, it will be difficult to extrude the ink from the perforated portion. The particle size of the extender pigment is not particularly limited as long as it does not disintegrate the emulsion ink, but in order to make it easier for the extender pigment in the oil phase component to remain on the paper surface together with the colorant, the fine particles on the paper surface used It is preferably larger than the pore size. When this particle size is small, the extender pigment penetrates into the paper together with other oil phase components, and the effect of adding the extender pigment is reduced. For example, when using high quality paper, it is preferable to use an extender pigment having a particle size of 2 to 3 μm or more. From a similar perspective,
A colorant having a large particle size may be used. However, if the particle size of the colorant is larger than the pore size on the surface of the paper, the color developability is adversely affected and the obtained print image property is deteriorated, which is not preferable.

The oil phase component may contain a colorant, a resin, a non-volatile solvent, a volatile solvent and an emulsifier in addition to the extender pigment. The colorant can be removed from the phase component. Known pigments are used as the colorant. For example, furnace carbon black for black and white, lamp black, acetylene black, carbon black such as channel black, copper, iron, titanium oxide, metals or metal oxides such as calcium carbonate, azo-based, cyanine-based, dioxazine-based, An organic pigment such as quinacridone is used. The resin in the oil phase component has the effect of improving the dispersibility of the extender pigment and the colorant in the oil phase and fixing them to the printing paper. For example, phenol resin, maleic resin, petroleum resin, alkyd resin, etc. Used.

As the non-volatile solvent, motor oil, spindle oil, machine oil, mineral oil such as liquid paraffin, and vegetable oil such as olive oil, castor oil and salad oil are used. As the volatile solvent, known mineral oil-based solvents and vegetable oil-based solvents are used. The use ratio of these solvents (nonvolatile solvent / volatile solvent) varies depending on the mixing ratio of the oil phase and the water phase, but is preferably in the range of 50 to 95/50 to 5 by weight. The emulsifier is used to form a W / O type emulsion, and a nonionic surfactant is preferably used. For example, sorbitan higher fatty acid ester (for example, sorbitan monolaurate, sorbitan monopalmitate, sorbitan monostearate, sorbitan tristearate, sorbitan monooleate,
Sorbitan sesquioleate, etc.), fatty acid monoglyceride, fatty acid diglyceride, and higher alcohols, alkylphenols, ethylene oxide adducts such as fatty acids, and the like.

The aqueous phase component in the present invention contains an O / W type resin emulsion and / or a water-soluble component in order to improve the dispersibility of the colorant and the fixing property to paper when the aqueous phase component contains a colorant. It is preferable to contain a polymer compound. As the colorant, the one used in the above oil phase component is used. Examples of the O / W type resin emulsion include polyvinyl acetate, ethylene-vinyl acetate copolymer, vinyl acetate-acrylic acid ester copolymer, polymethacrylic acid ester, polystyrene, styrene-acrylic acid ester copolymer, styrene-butadiene. Copolymer, vinylidene chloride-acrylic acid ester copolymer, polyvinyl chloride,
A resin emulsion such as a vinyl chloride-vinyl acetate copolymer or polyurethane is used. As the water-soluble polymer compound, polyvinyl alcohol, methyl cellulose,
Carboxymethyl cellulose, hydroxymethyl cellulose, polyvinylpyrrolidone, polyethylene-polyvinyl alcohol copolymer, polyethylene oxide, polyvinyl ether, polyacrylamide, gum arabic,
Starch, water-soluble urethane, etc. are used.

The amount of the resin component added to the aqueous phase component is preferably 20% by weight or less, and more preferably 10% by weight or less, in terms of solid content, based on the total amount of the emulsion ink. If the amount of the resin component added is too large and the ink is placed on the plate and left for a long period of time, the resin component may form a film at the perforated portions on the plate and prevent the ink from passing during printing. The water phase component may contain a surfactant or the like in order to improve the wettability and dispersibility of the colorant with respect to water. Further, if necessary, a water-soluble additive such as a wetting agent, an electrolyte, a fungicide, an antioxidant and a water evaporation inhibitor can be contained.

[0016]

EXAMPLES The present invention will now be described in detail with reference to examples, but the present invention is not limited thereto. In addition,
Parts in the examples mean parts by weight. Example 1 A (W / O) type emulsion ink was prepared by the following method with the composition shown in Table 1. First, an alkyd resin, furnace carbon black and sorbitan monooleate were added and sufficiently stirred, and then sufficiently kneaded with a three-roll mill. Next, calcium carbonate was added to No. 6 solvent and sorbitan monooleate, thoroughly stirred, and dispersed by a ball mill (stainless steel balls, 24 hours), and the kneaded material obtained above was added and mixed. 40 motor oil was added and sufficiently stirred to obtain an oil phase. Next, a water-in-oil emulsion ink was prepared by gradually adding an aqueous solution of water and ethylene glycol to the oil phase and stirring the mixture with a stirrer to emulsify it. The average particle size of the extender pigments shown in Table 1 is the centrifugal particle size analyzer (CAPA-).
700: manufactured by Horiba Ltd.).

Examples 2 and 3 and Comparative Example 1 In Example 1, titanium oxide and silica having acid values were used as extender pigments (Examples 2 and 3), respectively, and no extender pigment was used (Comparative Example 1). An emulsion ink was obtained in the same manner as in Example 1 except that the formulation shown in was used. The titanium oxide and silica used had their surfaces hydrophobized. Example 4 Example 4 was repeated except that the colorant was removed from the oil phase component and the colorant, dispersant, O / W type emulsion, water and ethylene glycol having the formulations shown in Table 1 were used as the aqueous phase component. An emulsion ink was obtained in the same manner as in Example 1. Comparative Example 2 In Example 1, except that the colorant and the resin were removed from the oil phase component and the colorant, the dispersant, the O / W type emulsion, water and ethylene glycol having the formulations shown in Table 1 were used as the aqueous phase component. An emulsion ink was obtained in the same manner as in Example 1.

[0018]

[Table 1]

<Test Example> Examples 1 to 4 and Comparative Example 1,
Each of the emulsion inks for stencil printing obtained in 2 was used to perform stencil printing on a high quality paper by a stencil printer (Lisograph RC115D (registered trademark) Ideal Science Co., Ltd.). The print density, strike-through, set-off, and bleed of the obtained prints were evaluated, and the print density when printing was performed on a lower grade paper (furnished paper) having irregularities on the surface by the following method, and the results are displayed. Shown in 2. (1) Printing Density: The printing density of the printed solid portion was measured with an OD meter (RD920 / manufactured by Macbeth). (2) Strikethrough: OD of the density on the back side of the printed solid part
It was measured with a meter (same as above). (3) Set-off: After 100 sheets were continuously printed, the stain on the opposite side of the printed surface was visually evaluated. The case where no set-off occurred was evaluated as ◯, and the case where set-off occurred was evaluated as x. (4) Bleeding: The bleeding state of the ink-adhered portion was observed using a microscope (80 times), and when there was almost no bleeding, it was evaluated as ◯, and when bleeding was noticeable, it was evaluated as x. (5) Printing density of lower grade paper: Evaluation was performed by the same method as (1).

[0020]

[Table 2] From Table 2, it was found that Examples 1 to 4 had higher print densities than Comparative Examples 1 and 2 and were excellent in strike-through and bleeding, and also had high print densities even when printed on lower grade paper. Also,
It was also possible to reduce set-off, which represents the permeation rate of ink.

[0021]

According to the emulsion ink for stencil printing according to claims 1 to 4 of the present invention, since the oil phase contains the extender pigment, the printing density is high and ink strikethrough, bleeding, etc. occur. The ink drying speed can be increased without any problem.

Claims (4)

[Claims] 1. Water in oil having an oil phase and an aqueous phase (W /
An emulsion ink for stencil printing, wherein the O) type emulsion ink contains an extender pigment in the oil phase. 2. The emulsion ink for stencil printing according to claim 1, wherein the extender pigment is contained in an amount of 1 to 50% by weight based on the total amount of the emulsion ink. 3. A colorant, a resin, a non-volatile solvent, in the oil phase,
The emulsion ink for stencil printing according to claim 1 or 2, which contains a volatile solvent and an emulsifier. 4. A resin, a non-volatile solvent, a volatile solvent and an emulsifier are contained in the oil phase, and a colorant and an oil-in-water (O) are contained in the water phase.
/ W) type resin emulsion and / or water-soluble polymer compound is contained.
The emulsion ink for stencil printing described above.